Bolted connectors have been widely used in high voltage applications, such as power stations and underground power distribution networks, for connecting electrical cables to other equipments such as main power supply cables or other electrical cables for forming cable networks.
Conventional bolted connectors are formed by several connector parts, which generally include a body part for receiving the part of the connector to be connected and one or more mechanical tightening parts, also-called keepers. The connector parts are assembled together around the conductor and brought into contact with the conductor by a number of bolts and nuts, thereby, establishing both electrical contact and contact pressure on the conductor.
An advantage of bolted-type connectors in comparison with other known types of connectors lies in their robustness, namely, against environmental conditions. However, since the quality of the electrical contact and the mechanical tightening strength of bolted connectors is directly dependent on the length of the connector and the number of mechanical tightening parts, several countries impose restrictions in terms of connector size and/or number of tightening parts in order to meet safety and performance requirements. For instance, several national specifications impose a connector design based on six tightening bolts.
Further, in order to establish a good electrical contact with the conductor, the connector parts are generally made of electrical conductive materials such as aluminium or copper alloys which render the connector relatively expensive. For these reasons, existing bolted connectors complying with current standards are generally bulky and uncompetitive in terms of cost.
An example of a conventional connector 100 compliant with the 6 bolt requirement and already installed in the market over the past 30 years is shown in FIG. 1.
The connector body includes three keepers 110, 120, and 130 that are longitudinally disposed, side by side, along a conductor 140 and separately fastened to the body member 150 by three pairs of fasteners 160, 170, 180 for mechanically tightening the conductor at three different regions. The fasteners generally consist on three pair of bolts, for instance M16 bolts made of aluminium alloy, and respective tightening nuts (not shown).
This design has the disadvantage that the connector is relatively long and requires the use of a substantial quantity of raw material in its manufacture, which makes the connector heavy and very expensive. For instance, commercially available connectors of three-keeper design have a longitudinal length of about 224 mm and weight 6300 g.
FIG. 2 shows another example of a connector 200 that has been available on the market since recent years and also compliant with the 6-bolts requirement. As shown in FIG. 2, the connector 200 includes a single keeper 210 that is fastened by three pairs of bolts 220, 230, 240 to the body part 250 for clamping a longitudinal conductor 260. In this configuration, the single keeper 210 essentially replaces the three separate keepers of the previous design which allows obtaining some reduction of the connector longitudinal length. Typical parameters of single-keeper connectors currently available on the market are 200 mm of longitudinal length of 5600 g of weight, which represents savings in raw material of about 11% with respect to the three-keeper connector. This is however not sufficient for rendering the connector cost competitive.
Further, the considerable weight of these types of connectors renders them difficult to handle and to install, for instance, in electrical cables at a certain altitude from the ground.
Thus, there is a need for electrical connectors compliant with customer requirements and which are less expensive and easy to install.